Electrical connector



p 1965 R. T. EVANS ETAL 3,208,030

ELECTRICAL CONNECTOR Filed Dec. 6, 1962 2 Sheets-Sheet 1 FIG. I

INVENTORS ROBERT I EVANS EDWARD C UBERBACHER ATTORNEY Sept- 1965 R. T.EVANS ETAL ELECTRICAL CONNECTOR 2 Sheets-Sheet 2 Filed Dec. 6, 1962United States Patent 3,208,039 ELECTRTCAL CONNECTOR Robert T. Evans,Yonkers, and Edward C. Uberbacher,

Poughkeepsie, N311, assignors to international Business MachinesCorporation, New York, N51! a corporation or" New York Filed Dec. 6,1962, Ser. l o. 242,728 9 Claims. (Cl. 339-47) This invention relates toelectrical connectors and to contact elements for electrical connectors.

An object of this invention is to provide an electrical connectorcomposed of two connector members having contact members therein whichare adapted to be connected to the ends of component leads, separatewires or wires of a cable, such connector members being matable andsimilar to each other in shape and size whereby any connector member mayserve either as a plug or as a receptacle.

Another object of the invention is the provision of an improvedelectrical contact element adapted to be mounted in a connector memberand adapted to provide an economical, effective and efficient electricalconnection with a contact element of another connector member, saidcontact elements being similar to each other in design, construction andassembly.

A further object is the provision of a contact element of the kind notedand adapted to be connected to the end of a conductor wire and theninserted, with the wire connected, into the body of a connector member,the contact element having multiple latching means for holding it in alldirections. However, the latching means is designed with flexible stopextensions subject to manipulation for outside release to permit removalof the contact element from either the front or rear of the connectormember.

Another object of the invention is the provision of an economical formof contact formed with both male and female elements of contact so thata connector comprising such contacts is of the interchangeablehermaphroditic type. The sheet metal contact is formed with both plugand socket features in addition to wire and cable securing means. Thecontinuous serpent form of the contact provides a plurality of points ofcontact when a pair is brought into wiping engagement.

An object of this invention is to provide insulated electrical connectormembers and formed sheet metal contact elements therefor of the abovementioned character which are relatively simple, economical and easy tomanufacture and assemble and still are rugged in construction andreliable in operation. A bellows formation of the contact adds to theflexibility of it and also provides two extensions to be engaged by twoopposite extensions so that between them there is a double pinching andwiping action for each pair of interengaged contacts. Attachment of awire to a contact is optionally by crimping, soldering or welding.

An important object of the invention is the design and proportioning ofa contact element with small functional area to save on the cost ofplating. Since gold plating comprises a large part of the cost of lowvoltage contacts, an important saving is effected by the present design.The contact element is of miniature size and the functional contactareas are kept small and isolated or raised so that resist material maybe coated on most of the contact element when it is being partiallyplated, and therefore the selective plating of gold is limited to thesmall functional surfaces.

The invention is notably useful when embodied in an electrical connectorhaving a plurality of contact elements for closing a multiplicity ofelectrical circuits. The connector members are adapted to be formed inany size or from a plurality of grouped structural units permitting alarge number of contact elements to be assembled easily for constitutinga connector member.

The foregoing and other objects, features and advantages of theinvention will be apparent from the following more particulardescription of the preferred embodiments of the invention, asillustrated in the accompanying drawing.

In the drawing:

FIG. 1 is a perspective view of a form of contact element of the presentinvention.

FIG. 2 is a sectional elevation View of a pair of novel connectormembers containing the novel contact elements.

FIG. 3 is a detail perspective view of the opening or inner chamber ofan insulation connector body which is designed to receive and hold acontact element.

FIG. 4 is a sectional elevation view taken along line 44 in FIG. 2 andshowing the wiping surfaces of contacts as connected.

FIG. 5 is a perspective view of another variety or embodiment of thetype of contact element shown in FIG. 1.

A main object of the invention is to provide a better interchangeableform of multiple electrical connector in which the contacts make abetter electrical connection, are more easily inserted and removed forassembly and replacement, require less force for mating, and in additionare economical in construction. All this is accomplished by the novelformation of a common insulation block and a universal form of contactdesign wherein the contact is one thin flexible strip of metal formedwith a stiffened center portion as a base for three kinds of extensions:stop extensions, mating extensions, and wire securing extensions. Thestop extensions are oppositely facing to hold an inserted contact in theinsulation block in both directions and, furthermore, such stops areflexible and suited for manipulation from the outside of the block sothat a contact may be inserted or withdrawn in either direction. Themating extensions are each formed with several serpentine folds, bellowsstyle-the first two folds being brought close together while a thirdouter fold is brought out with a wide radius to extend flexibly over theother folds and superimpose a curved tip over the bent end of the otherfolds, whereby interengagement of blocks and two sets of extensionseffects a double pinching and wiping engagement because the twocontacting inner folds are pinched between the curved tips of the twoouter folds to effect a very reliable form of dual electrical contactfor each mating point. The wire securing sections serve to clamp theinsulation and wire portions of a conductor to the contact end to act asa strain relief retainer for a solder or weld connection of the wire tothe contact. Each universal insulation block is formed with a pluralityof contact receiving openings, each opening having an inner stopshoulder terminating a ramp formed on the floor of the opening, and arabbet formed alongside one inner corner of the opening wherein acontact edge may be confined to securely hold the entire contact member,said opening and said rabbet extending all the way through said block,whereby a contact may be inserted or withdrawn in either directionthrough said opening.

Referring to the drawing in greater detail, there is shown an electricalconnector of this invention comprising two connector members which aredesignated, generally, by the reference numbers 20 and 21, respectively.The two connector members 20 and 21 of the illustrated embodiment aresubstantially identical to each other in their details of constructionand are adapted to be interengaged, as shown in FIG. 2 of the drawing,for interconnecting a contact element or terminal 22 of member 20 with asimilar contact 23 of member 21. Each of the contact elements is adaptedto be separately connected (as explained hereinafter) to the ends ofconductors 24, whereby the electrical connector serves to join theconductors of one connector member to the conductors, respectively, ofthe other connector member.

Each connector member comprises a body or block or 21 formed ofnon-conducting material. Although any plastic material such as asynthetic polymer, e.g., nylon, is a preferred material from which toform the block, other insulation materials as ceramics and hardernon-conductors are usable. A full block 20 or 21 is either square orrectangular in outer form and provided with one or more openings orholes 25, each hole designed to receive and hold a contact element 22 or23. The holes 25 are usually arranged in regularly spaced rows andcolumns for multicontact connectors, but one pair of coinciding holes 25as shown in FIG. 2 is believed ample showing to illustrate theprinciples of the invention.

FIG. 3 shows how the inside of the openings 25 is formed to facilitatethe insertion of a contact element, the retention of the element and themating of two such elements. A wide opening floor area 26 is joined to asloping ramp area 27 which has constricted side shoulders 28 as innerends of flared opening with one wing 29 coinciding with the wide floorarea 26. The sharp corner edge 30 of the hole opening is engaged by onecontact tab or lug to hold the contact in place and blocked frommovement to the right, while the edge 31 is engaged by a retainer fingeron the contact to hold it from movement to the left. A slot, notch orrabbet 35 is formed along one side of hole 25 at the near side as seenin FIG. 3.

Referring to FIGS. 1 and 2 of the drawing, a contact element or terminal22 is shown as formed from a single elongated flat strip of metal suchas spring stock of copper alloy or Phosphor bronze. For ease ofdescription the terminal strip may be described as comprising a contactengaging front end portion as bellows 36 terminating with an end springleaf 37, a conductor-connecting rear end portion 38 terminating with anend pair of wings 39, and a middle portion 40 between said end portions.

A conductor retaining pair of sides 41 is formed by bending the sideedges of the terminal strip toward each other to provide a well forsolder or a confined spot wherein the end of the wire 42 may be weldedonto the contact. This inner bend is continued to form the wings 39which are to be crimped around the outside surface of an insulationjacket or coating 24 of the wire signal conductor 42. Thus a conductorwire is secured both mechanically and electrically in a strong fashionto the rear end of a contact 22.

An important aspect of the invention resides in the feature that thecontact terminals are adapted to be connected to the ends of theconductors and then inserted into the blocks of the connector members,or retracted therefrom in either direction, and when once in such blockthey remain in position tightly and secure against being accidentlyloosened or withdrawn. For such securance, the middle portion 40 of thecontact has a spring retainer or stop finger 45 struck from it leavingan opening 46 in the strip. The spring finger 45 extends longitudinallywith respect to the strip contact 22 with that end of the finger whichis remote from the conductor end portion of the strip, integral with thestrip, while the other end of the finger is free. Thus the finger may bepressed toward or partially into its opening 46, as when the contactstrip 22 is being inserted into the insulation block 20, and then thefinger 45 will spring outwardly, when free of block hole restraint, tothe position shown in FIG. 2, whereby the end of the finger engages theshoulder 31 formed on the inside of the block to prevent withdrawal ofthe terminal contact from the block in a direction to the left. In orderto prevent displacement of the assembled contact terminal toward theright, it is provided with another stop extension in the form of anoffset lug or tab 47 which is bent out of a rear extension of a sidewall 48 formed on one side of middle portion 40 of contact strip 35. Tab47 engages around the edge 31, FIG. 3, of the hole 25 in block 20 and ison the thin extension 49 which is flexible enough to permit manualforcing of the tab into the hole should it be desired to remove the leftcontact through the hole 25 toward the right, FIG. 2. For manual removalin the opposite direction of the same contact, FIG. 2 compression offinger 45 upward to free it from shoulder 31, frees the contact forremoval toward the left. From the foregoing it is clear that a contactmay be inserted into the block hole 25 from either side and lockingparts 45 and 47 will snap into locking positions, but both said partsmay be manipulated to permit retraction of the contact in eitherdirection with or without a conductor attached.

The side wall formation 48 in rising from the flat midsection 40 of thecontact, provides an L shaped crosssection which is a strong foundationfor the spring leaf end of the contact. The upper edge of side wall 48also forms a broad cooperating surface with the inside of block hole 25just as the flat middle area 40 rests on the floor of the hole and theedge of area 40 fits into the rabbet or slot 35 to seat the contactfirmly therein.

The contact engaging or wiping end of contact 35, FIG. 1, is narrowerand more flexible than the middle portion 40 and it comprises a sort ofbellows fold of strip with portions 50, 52 and 54 folded back and forth,portion 52 being the penultimate fold. Adjacent portions 50 and 52 arefolded close together and at the bent end define a short raised platformover a narrow slot 51 which is allowed to remain open because a radiusof small size (about equal to thickness of stock) is better than a sharpbend with respect to distributing the stresses at the bend of relativelyhard spring stock. The outer pair of folded portions 52 and 54 are morewidely spaced to define a relatively wide curved end 53 which is aflexible base for the upwardly flared outer spring leaf wiping blade 37.The spring bellows design of folded portion 40, 52, 54 provides a veryflexible sort of wiping contact which readily accommodates itself tomating with a similar contact under adverse conditions of beingreceptive to any one of thousands of similar blocks which are not alwaysidentical in size or perfect in contact disposition.

The manner in which the contact terminals of c0nnector member 20interengage or mate with respective contact terminals of connectormember 21 appears best in FIG. 2. Referring in particular to the wipingcontact areas of portions 50, 52 and 37 of contact 22 at the left inblock 20 as duplicating those of FIG. 1, and a similar contact in block21, these being in alignment for interengagement and being inverted withrespect to each other, it will be noted that the fold 50, 52 of the leftcontact fits between the fold 52, 54 of the right contact and the samecondition is duplicated with regard to the other pair of folds.Therefore, a novel form of double pinching and wiping engagement iseffected between joined contacts. The sectional view, FIG. 4,illustrates how there are three lines of wiping contact betweenterminals 22 and 23 when forced together. This wiping area, encircled as55 in FIG. 1, is comparatively small and near the contact ends and thusaccessible and limited to use of small amounts of precious metal platingto gain economical use of such costly coatings.

The normal spacing between the middle bellows fold 52 and the contactleaf 37 is smaller than the end thickness of 50, 52 so that when thecontacts are mated there is flexure of the leaf 37 and pressure duringwiping engagement and thereafter as the contacts remain connected.

Blocks 20 and 21 may have holders or shrouds (not shown) which also actas assembly guides to lead the contact fold 50, 52 into the opening 37,52 of the other contact. However, since the contact ends extend, in thecase of only one or a few mating points, the contacts may be broughttogether without mechanical guidance.

An alternative form of the contact or terminal 22 is shown in FIG. 5.There it is seen that many features such as the bellows of a fold 61comprising contact portions 60, 61 and 64 are the same as the othercontact. However, the midportion is stiffened further by the addition ofan extra side wall so that one side wall portion 66 is plain and theother wall 65 is formed with a flexible extension 68 which is formedwith a bent lug or tab 67 which acts as a movable stop similar to stop47. The wing ends 69 for grasping conductor '24 are simple in formbecause the wire 42 has its end welded, soldered or secured directly tothe bent area 70 which is a broad and relatively immovable area of thecontact leaf 64. Also present is a stop finger 75 similar to finger 45.

It is obvious that the contact terminal of FIG. 5 will fit into anopening 25 of a block such as blocks 20, 21 without the need for rabbetor slot 35 and there serve in all ways like the contacts describedhereinbefore. The block opening 25 may be symmetrical in the case of theuse of the contact of FIG. 5, i.e., the flared wing 29 is to beduplicated on the near side of the opening when slot 35 is omitted.

While the invention has been particularly shown and described withreference to preferred embodiments thereof, it will be understood bythose skilled in the art that the foregoing and other changes in formand details may be made the-rein without departing from the spirit andscope of the invention.

What is claimed is:

1. A contact comprising a single strip of thin flexible metal having,

an L shaped stiffened midsection,

a pair of opposite stop extensions formed to extend from said stiffenedmidsection,

a reduced width portion at one end of said contact, said portion beingformed with a plurality of folds, bellows style, and a final foldextending as a contact leaf, said folds being proportioned and arrangedto receive the folds of a similarly shaped contact for mating electricalengagement,

and a conductor clamping portion on the other end of said contact.

2. A contact of the kind set forth in claim 1 wherein,

one of said stop extensions is a flexible reduced portion extension ofthe side wall of the L shaped midsection,

and the other stop extension is a finger struck down out of the base ofthe L shaped midsection.

3. A contact of the kind set forth in claim 1 wherein,

said reduced width portion has a first fold, sharply bent to lie againstthe base of the L shaped midsection except for a slightly raised portionnear the fold bend,

and a second fold with a comparatively large radius rbend out of thefirst fold to form a free contact leaf coextensive with said first fold,said leaf having a curved end opposite said raised portion for limitedarea wiping contact reception of an inserted contact.

4. A connector block of insulation material,

a contact receiving formation in said block formed around an opening insaid block comprising,

a shoulder terminating a sloping ramp formed on the floor of saidopening,

a flared entry into a reduced width wall for said ramp, and

a full length rabbet formed alongside one edge of said opening wherein acontact edge may be confined,

whereby an L shaped contact may be fitted into and tightly held in saidOpening and rabbet with the outer sides of the L shaped contact confinedby the opening walls and the one edge of the L shaped contact confinedin said rabbet, both said opening and said rabbet extending through saidblock from one outer face to another outer face, whereby a contact may 6be inserted or withdrawn in either direction through said opening.

5. A contact of a single formed strip of thin flexible metal comprising:

a U shaped midsection,

a pair of opposing stop extensions formed on said midsection,

an elongated reduced width portion at one end of said I contact, saidreduced portion being formed as a plurality of flat folds, bellowsstyle, the first two folds I being bent at a small radius which is aboutequal to .the thickness of said strip, said folds forming a slightlyseparated portion as a short raised platform near the bend, and beyondthe platform .said folds are folded close together with the second foldseparating with a wide radius into the final fold, said final foldextending as a .free contact leaf with a curved end opposite saidplatform, and

a conductor clamping portion formed on the other end end of saidcontact.

'6. A contact terminal for an electrical connector which comprises,

a thin contact element having front, middle and rear ,portions,

means on said rear portion for engaging an electrical conductor,

said middle portion being formed as a relatively stiif L I shapedsection,

flexible stops formed on said middle portion for contact retention intwo directions when in a holder but flexibly disengageable bymanipulation for retraction of said contact from such a holder in eitherdirection,

said front portion is stock bent as a bellows of three folds including apair of contact leaf extensions, one relatively stiff formation offolded layers and the other of a singular curved free end formation,

whereby said leaf extensions are interengageable in overlying positionwith respective extensions of a similarly constructed contact terminal,with said free end formations of each contact resting on a foldedextension of the other contact with said folded extension pinchedbetween the pair of extensions of the other contact.

7. -An electrical connector member comprising,

a body of non-conducting material having an opening extendingtherethrough,

a thin angular bent con-tact element disposed in said opening,

said contact element having front, middle and rear portrons,

means on said rear portion for engaging an electrical conductor,

said middle portion being stiffened with one or more angular bent edges,

said front portion including a pair of contact leaf extensions, one witha straight end and the other with a curved lead-in end,

whereby said leaves are interengageable in reverse overlying positionswith respective leaves of a similarly designed contact element, with thestraight ends overlapping and in contact and the curved end of eachelement pressing on the straight end of the other element in doublepinching engagement.

8. An electrical connector comprising:

a connector .block of insulation material having a con tact receivingformation formed around the walls of an opening therein where there is,

a stop shoulder terminating a sloping ramp formed on the floor of saidopening,

a flared entry into a reduced width wall for said ramp, a full lengthnotch formed alongside one inner wall of said opening to receive an edgeof a contact, both said opening and said notch extending through 7 saidblock from one outer face to another outer face, a contact fitted insidesaid opening and notch, said contact being a single strip of thinflexible metal strip, said folds near the bend forming a slightlyseparated portion as a short raised platform, and beyond the platformsaid folds are folded close together, with the penultimate foldseparating from having an L shaped stiff midsection and an extend- 5 theassociation with a wide radius into the final fold, r ing contactportion, and l said final fold extending as a free contact leaf with a Pof pp p extensions formed 011 said a curved end opposite to saidplatform, whereby section to cooperate with the face and stop shoulderof similar pairs of platforms and curved ends of two Said block, one OfSaid p extensions being a flexible identical contacts may beinteren-gaged and establish reduced portion extension of the side wallof the 10 mated Wiping Contact L shaped midsection, and the other stopextension being a flexible finger struck down out of the base ReferencesCit d by the Examiner of the L shaped midsection, said extension flexurepermining manipulation, UNITED STATES PATENTS whereby said contact maybe inserted or withdrawn in 5 2,486,235 10/ 49 Hurst X either directionthrough said opening. 2,539,230 1/ 1 C g 339*278 X 9. An electricalcontact formed to provide electrical 2,882,512 4/59 Morone 339--193connection with a similar contact when in mating holders 2,891,103 6/59Swengel 339-426 X and comprising a single strip of thin flexible metalformed 2,935,720 5/60 L i 339-205 X with an L shaped stifienedmidsection, and 20 2 933,190 5 50 hbi l 339 217 X stop extensions formedto extend from said stiffened 3,058,091 10/62 Henschen 339 217 Xmidsection to cooperate with said holder, 3 065 441 11/62 Leonard 39 9 aconductor clamping portion formed on one end of 3:069:65? ,12/62 Grew339 217 X g g g g fg f t the th nd 3,072,340 1/63 Dean 339-49 an e 0 gae11cc W1 P 1011 a 0 er 6 25 3,083,345 3/63 Scheller 339 47 of saidmidsection, said reduced portion being formed as several serpentinefolds, bello'ws style, the bend of the first two folds being bent at asmall radius which is about equal in size to the thickness of the JOSEPHD. SEERS, Primary Examiner.

ALBERT H. KAMPE, Examiner.

1. A CONTACT COMPRISING A SINGLE STRIP OF THIN FLEXIBLE METAL HAVING, AN L SHAPED STIFFENED MIDSECTION, A PAIR OF OPPOSITE STOP EXTENSIONS FORMED TO EXTEND FROM SAID STIFFENED MIDSECTION, A REDUCED WIDTH PORTION AT ONE END OF SAID CONTACT, SAID PORTION BEING FORMED WITH A PLURALITY OF FOLDS, BELLOWS STYLE, AND A FINAL FOLD EXTENDING AS A CONTACT LEAF, SAID FOLDS BEING PROPORTIONED AND ARRANGED TO RECEIVE THE FOLDS OF A SIMILARLY SHAPED CONTACT FOR MATING ELECTRICAL ENGAGEMENT, AND A CONDUCTOR CLAMPING PORTION ON THE OTHER END OF SAID CONTACT. 